1. Field of the Invention
The present invention relates to a method and to an apparatus for controlling an inertial system. In particular, the present invention relates to a technique for suppressing vibration in an inertial system.
2. Description of Related Art
A mechanism, in which a motive power generator and a load machine, which are inertial bodies, are coupled via an compliant torque transmission element, is a two-inertia system. When the motive power generator produces abrupt acceleration or deceleration, a deviation occurs between the position and speed of the motive power generator and those of the load machine in the two-inertia system. Thus, if a typical servo control device is used to control the two-inertia system, the system stability decreases, and vibration occurs on load machine.
The typical servo control device has a rotation detector on the side of the rotational motive power generator. Therefore, when the stiffness of the torque transmission element is so low that the load machine is not regarded as a rigid body, the motion of the load machine is delayed because of the torsion of the torque transmission element. Thus, although the motive power generator can follow the position command, the load machine can no longer follow the position command, and as a result, vibration occurs on load machine.
As a solution to this problem, for example, Japanese Patent Laid-Open No. 10-56790 discloses a vibration suppression approach that suppresses vibration in a two-inertia system by removing a vibration component from an operation command. According to this vibration suppression method, the operation command is filtered by a vibration suppression filter having the same frequency characteristics as a notch filter, thereby suppressing a gain peak due to an anti-resonance frequency.
However, in the conventional vibration suppression apparatus there is a possibility that the motion of the load machine is slowed, or that the response of the load machine to the operation command is delayed, because of the responsiveness of the vibration suppression filter.